Control circuit for switching telegraph facilities



Feb. I, 1949.

\ G. R. PIGMAN CONTROL CIRCUIT FOR SWITCHING TELEGRAPH FACILITIES Filed Sept. 1, 1944 UB QO m orm QB QQU Fl.

' IINVENTOR G. R. Feynman ATTORNEY Patented Feb. 1, i949 f NIT D STAT RATEJNT OFFICE- atsgact, I

ApplicationSeptember 1, 19i'4, -serai No. 552,252

3Claims. (ctivezy Thisinvention relates to telegraphcircuits and I particularly to arrangements whereby different telegraph receiving instrumentalities may befselectively switched into receiving condition bythe transmission of chosen combinations of telegraph code signals from a distant point.

' In telegraph systems, and particularly inteletypewriter systems, occasions frequently arise where it is desirable that the transmittedmessage be received by one only of several receiving devices. Accordingly, arrangements have heretofore-been devised whereby the sending operator may switch a desired receiving instrument into receiving condition. This has usually been done by transmitting certain combinations of teletype code signals to control distant switching facilities.

One of the objectsof the present inventionis to accomplish the results above described by arnangements which are simpler than those previously employed.

Another objector the invention is to arrange receiving devices so that when one is receiving it responds to a special code combination to'operate a switching relay which disables it and switches in theother receiving device. The switching relay is then locked up over a circuit so controlled by the second receiving device that the latter unlocks the switching relay when the same or another special code combination is later receivedi It thereupon disables the second receiving device and switches the first back into receiving condition.

The invention will be more fully understood from the following description when read in con nection with the accompanying drawing in which the figure illustrates the principles of the invention applied to the control from a distant point of the selection of either of two teletypewriter receiving mechanisms.

Referring to the drawing, a line L incoming from a distant point terminates in two line relays LE1 and LE2. Each of'these relays operates a separate teletype receiving mechanism only certain parts of which are illustrated as these mechanisms are well known in the art. These receiving mechanisms, shown generally within the dotted line rectangles R1 and R2, may be page printers, tape printers, typing reperforators or other devices well known in the art. l

As illustrated, the receiving instruments are typing reperforators, because suchinstru'ments are especially useful, as will appear later, where messages from a distant point are to be relayed at an intermediate point to other stations a Mulhliw 2 reachedby separate routes. One of theseinstru ments, the receiver Ri, includes a selecting magnet'SMroperated by the contact of the line relay,- ,I-l?.1,- This selecting magnet is used to control the selection, by means of comb bars or other well-known devices which are not illustrated, of mechanisms such as type bars for printing different characters or of stunt mechanisms for controlling the incidental operations of the printing mechanism. These mechanisms may also be used in a known 'mannerto operate contacts. For further information as to how this maybe accomplished, reference is made to the patents to Beattieet al., No. 2,120,235, issued June 14, 1938, and to Duncan, No.-2,321,372, issued June 8, 194.3. ,Ordinarily, as shown in the patents to Beattie et al.,.and Duncan ,above referred to, the contacts are operated by pull bars which actuate the type bars or stunt mechanisms and this holds true whether the, receiving 'mechanism be a page printer, aftape printer or a typing reperforator.

the case of the typing reperforator the selective mechanisms which are used to control the printing'operations are also used to control the punching of holes in the tape in accordance with the Baudot code, so that the tape maybe used to repeat or relay themessage overthe line to some distant point by passing the tape through a' suitable jtransmitter (not shown). In the typingjreperforator the printing mechanism is generally used to print the characters upon the same tape whichis perforated in accordance with the message This is to enable the receiving operator to read ily read the message if desired before it isrelayed. The ,receiver R1 includes normally open contacts [SCrand F01 which are used in controlling th'switching mechanism to be described hereinaf, I Ifhese contacts are controlled by the selectiv mechanism of the receiver in a wellkn-own manner as shown in the patents to Beattie 'et al. and Duncan above referred to. The contacts S61 and F01 are used to operate, the control relay CRwhich performs the switching operation as will be described later.

In order to operate the control relay CR both contacts must be closed. The contact F01 is closed when the Baudot code for figures is received and remains closed'until its release'upon receiving the letters signal. As is well known in teletype systems, the characters and stunts are divided into two groups: (a) letters, which are'fusually capitals and are transmitted in the form of different Baudot code combinations, and

*( h figures, punctuation marks, stunts, etc.,

as above stated. If, after the fi urescontacthas contact of the line relay LRi.

called letters code which conditions the receiver to print letters. On the other hand, when socalled figures are to,.:be printed, ether-term fi'ga ures including also pun-ctuationmarks,stunts, etc.,the,figures code precedes the characters or. stunts which are to be recorded in order to con dition the printer for that purpose. I

With the arrangement above described; IiwhBn: the. figures contact FCi is operated, it then .re: mains operated until released by the lettersgcode,

been closed, the special selector contact SC1 corresponding to a particular Baudot code is momentarily operated, a circuit is closed through,

the contacts S01 and F01 to operate the control relay CR. The manner in which the control relay GR operates will be described later.

A second receiving instrument-R2 is also provided and is arranged to'be controlled by the line relay LRz. This second receiver is similar to the receiver R1 and includes a selecting magnet SM2 operated by the contact of the line relay-LE2, and performing functions similar to those of the selecting magnet SM; of the receiver R1. The receiverRz also includes a figures-contact FCz and a selective contact SC similar to the correspondingcontacts; of relay R1. 'However, there is this difference to'be noted, that whereas the contacts of the receiver R1 are-normally open; the contacts of the receiver R2 are normally closedand in parallel. These contacts are operated in the same manner as described in connection with the corresponding contacts of receiver Rn. i

The control-relay CR is providedwith contacts l .2 which when closed will complete a locking circuit whose purpose will be described later. It also has a pair of contacts 3-4; which are normally open but, when closed, short-circuit the Likewise;.it has a'pair of contacts 5-6 which, however, arenormally closed and when so closed, short-circuit the armature of line relay LRz.

It will now beevident that in the normal conmitted as already described. This is, of course,

the normal operation of a teletype receiver.

If now the distant operator with the figures contact FC'I closed later sends the special code to operate the selector contact S01, a circuit will be completed from battery over said contact SC1 ands-rover the :contact F61 :through. the winding 0f"tlie"'re1ay CRrto ground; This operates the relay CR. By closing its locking contacts I and 2; the relay CR is locked over a circuit passing overrnormallyggclosed contacts S02 and FC2 of receiver: R2. When thus locked up, the control 1 rel-ay CR, will remain actuated until the locking circuit; is opened in a manner to be described later. Tha -control; relay upon being operated closes its contacts 3 and 4 and thereby disables the line relay LE1; Consequently, the receiver R1 dition of the circuit, with the contacts S01" and SC2 open and the control relay CRl not actuated, the contact of the line relay LR: is short-circuited and therefore the receiver Re fwill'fnot respond to signals coming in over the line L.

The armature of the line relay LRt however, is

not short-circuited at the contacts 3-4 andgany signals which come in over the line Lwillb'e re!- ceived by the receiver R1 to operate the printer through the selective magnet 8M1. A150, if reperforating apparatus is provided the select ing magnet will cause thereperforatorto per; foratethe message in the tape. If the reperr forating apparatus is not provided, the .message will be'recorded by printing eitherupona tape or upon a sheet of paper, depending upon whether the printer is a tape printerpr a page printer. c N If the distant operatorwishes to record ;upon the receiver R2, she will sendthe code-to .,operate willy-no longer receive messages transmitted over the line L. By openingzits contacts 5 and 6, the control relay cR removes a shortrcircuit from aboutgthe' contact of the line relay LR This line relay is now in condition, to operate the selector magnet SMz of the receiver R2, and consequently .the receiver R2 will receive subsequent signals from the line until- 'the' codev combination for switching is again transmitted.

' This code combination for switching 1 may be the same identical; combination. thatjwas used to, operatethe contacts S01 and H31 in the case of receiver E1., In other words,xif while the control relayfiR is lockedj'up andtthe'receiver Re isj receiv n a distant operator transmits a figures. code followedby a' code for operating the ehdorccntact s02, b t jicc act C $02 '(whichjare in.parallel are' operated and will open the locking circuit of the control relay, CR Whichis released. The contacts SC2 andFCz are connecteddn ,.parallel so that, the locking circuit will, not be opened ,nntil bothofgthese contacts are simultaneously "opened;

While theuse of .'.the same, code. is permissible ioroper-ating contactsSC'if-and FCrto switch to one, receiver, and .for. operating contactsfic j and F02. to switch. backsthere, are .cert.a in, advanmachine will receive the message. Thejoperator the figures contact F01, unless the figures-code has, already been sent in connectionwithfinal characters ofthe message, as for example, where the final characters happen to befigures, punctuation marks, or stunt controls. In either case,

, when the .figurescontact:FC'rhas been;.closed it remains closed until the letters code is transneed not remember what machine w.as ..receiving 55 previously,, as ..would betnecessary. if, the same code combination were. used .for, switching. both ways. 1

llvheri tl e re1 ay, -CR., releases, its;..contacts. -5 and .6. willjagain be closed to disablethe line relay LR; and hence the receiver R The 0105-,- ing. otthe icontacts '3 and. 4 of the control, relay CB .removessthe short-circuit from, the. Contact of .theyline relay; LRt aand, thereceiver R; is ac:- cordingly conditioned. to receive. I. The receiver Rr-WilL continue. to ,responduto.v signals. until .the

special switching, code, is received, when. the

switch,ing .operatitme previously. described will As already state s, the control relay with its operatiing and {locking circuit, controlledby the contacts of; the two; receivers may ibe used with either page printersorgtape printerswithout any reper forating; mechanismv bein provided. How.- ever the inventionr sis particularly, usef ul where thesrece vina i str men s R1 1- 2; ar t p n reperforators. These instruments, as has already stations located on difierent outgoing lines. With an arrangement such as illustrated and herein described, where typing reperforators are employed, the operator at the relaying point where the reperforators are located, will know that all tape she removes from one reperforator is to be sent out over a transmitter to one particular line, whereas all tape taken from the other reperforator is to be sent out over a transmitter connected to a second outgoing line. The operator at the relaying point is thereby relieved of the burden of ascertaining by inspection of the message the line over which it is to be routed. The distant sending operator is able to control the routing of the message at the receiving station by sending the special combination of signals which switches from one reperforator to the other.

It will, of course, be understood that the receiv-- ing instruments R1 and R2 may be reperforators which are not arranged to type messages. This merely involves leaving out the printing mechanism. The switching contacts are of course controlled and operated by the same mechanical devices which serve in the typing reperforator to actuate'the printing mechanism and also the reperforating mechanism.

While this invention has been disclosed in certain specific arrangements which are deemed desirable, it will be obvious that the general principles herein set forth may be embodied in many other organizations, widely different from those illustrated, without departing from the spirit of the invention as defined in the appended claims.

What is claimed is:

1. In a teletypewriter system, a pair of teletypewriter receivers at a station responsive to Baudot code signals transmitted from a distant station, a switching relay having contacts and normally conditioning one of said receivers for reception of Baudot code signals and disabling the second receiver, said receiver thus conditioned having a contact responsive to a case shift signal and another contact responsive to reception of a predetermined Baudot code signal other than a case shift signal, a circuit closed when both of said contacts are in actuated condition for actuating said switching relay, means controlled by said switching relay when actuated to lock up said switching relay, circuits in which contacts of said switching relay are interposed to disable said first receiver when said switching relay is actuated and at the same time to condition said second receiver to receive Baudot code signals, said second receiver having a contact responsive to a case shift signal and another contact responsive to reception of a predetermined Baudot code signal other than a case shift signal, and circuit means adapted to unlock said switching relay when said contacts of said second receiver are simultaneously actuated.

2. In a teletypewriter system, a pair of teletypewriter receivers at a station responsive to Baudot code signals transmitted from a distant station, a switching relay having contacts normally conditioning one of said receivers for reception of Baudot code signals and disabling the second receiver, said receiver thus conditioned having a contact responsive to a case shift signal and another contact responsive to reception of a predetermined Baudot code signal other than a case shift signal, a circuit closed when both of said contacts are in actuated condition for actuating said switching relay, means controlled by said switching relay when actuated to lock it up, electrical circuit means including contacts actuatable by said switching relay interposed in circult and arranged to disable said first receiver when said switching relay is actuated and at the same time to condition said second receiver for reception of Baudot code signals, said second receiver having a contact responsive to a case shift signal and another contact responsive to reception of a predetermined Baudot code signal different from any of the above-mentioned Baudot code signals, and circuit means adapted to -unlock said switching relay when said contacts of said second receiver are simultaneously actuated.

3. In a teletypewriter system, a pair of teletypewriter receivers at a station responsive to Baudot code signals transmitted from a distant station, a switching relay having contacts normally conditioning one of said receivers for reception of Baudot code signals and disabling the second receiver, said receiver thus conditioned having a contact responsive to a case shift signal and another contact responsive to reception of a predetermined Baudot code signal other than a case shift signal, a circuit including a series connection of said contacts adapted to be closed when both of said contacts are in actuated condition for actuating said switching relay, means controlled by said switching relay when actuated to lock it up, electrical circuit means including contacts actuatable by said switching relay to disable said first receiver when said switching relay is actuated and at the same time to condition said second receiver for reception of Baudot code signals, said second receiver having a contact responsive to a case shift signal and another contact responsive to reception of a predetermined Baudot code signal different from any of the above-mentioned Baudot code signals, and a circuit including a parallel connection of said contacts of said second receiver adapted to unlock said switching relay when said last-mentioned contacts are simultaneously actuated.

GEORGE RUEMONT PIGMAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,199,262 Gell Sept. 26, 1916 2,023,952 Dirkes Dec. 10, 1935 2,129,741 Levy Sept, 13, 1938 2,179,712 Burcky Nov. 14, 1939 2,304,775 Blanton Dec, 16, 1942 

